//===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
-//
+//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
//===----------------------------------------------------------------------===//
//
// This pass is used to ensure that functions have at most one return
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Type.h"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Function.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iPHINode.h"
-#include "llvm/Type.h"
-
-namespace llvm {
+using namespace llvm;
-static RegisterOpt<UnifyFunctionExitNodes>
-X("mergereturn", "Unify function exit nodes");
+char UnifyFunctionExitNodes::ID = 0;
+INITIALIZE_PASS(UnifyFunctionExitNodes, "mergereturn",
+ "Unify function exit nodes", false, false)
-Pass *createUnifyFunctionExitNodesPass() {
+Pass *llvm::createUnifyFunctionExitNodesPass() {
return new UnifyFunctionExitNodes();
}
void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
// We preserve the non-critical-edgeness property
AU.addPreservedID(BreakCriticalEdgesID);
+ // This is a cluster of orthogonal Transforms
+ AU.addPreservedID(LowerSwitchID);
}
// UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
// return.
//
std::vector<BasicBlock*> ReturningBlocks;
- std::vector<BasicBlock*> UnwindingBlocks;
- for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
- if (isa<ReturnInst>(I->getTerminator()))
- ReturningBlocks.push_back(I);
- else if (isa<UnwindInst>(I->getTerminator()))
- UnwindingBlocks.push_back(I);
+ std::vector<BasicBlock*> UnreachableBlocks;
+ for (BasicBlock &I : F)
+ if (isa<ReturnInst>(I.getTerminator()))
+ ReturningBlocks.push_back(&I);
+ else if (isa<UnreachableInst>(I.getTerminator()))
+ UnreachableBlocks.push_back(&I);
- // Handle unwinding blocks first...
- if (UnwindingBlocks.empty()) {
- UnwindBlock = 0;
- } else if (UnwindingBlocks.size() == 1) {
- UnwindBlock = UnwindingBlocks.front();
+ // Then unreachable blocks.
+ if (UnreachableBlocks.empty()) {
+ UnreachableBlock = nullptr;
+ } else if (UnreachableBlocks.size() == 1) {
+ UnreachableBlock = UnreachableBlocks.front();
} else {
- UnwindBlock = new BasicBlock("UnifiedUnwindBlock", &F);
- new UnwindInst(UnwindBlock);
+ UnreachableBlock = BasicBlock::Create(F.getContext(),
+ "UnifiedUnreachableBlock", &F);
+ new UnreachableInst(F.getContext(), UnreachableBlock);
- for (std::vector<BasicBlock*>::iterator I = UnwindingBlocks.begin(),
- E = UnwindingBlocks.end(); I != E; ++I) {
+ for (std::vector<BasicBlock*>::iterator I = UnreachableBlocks.begin(),
+ E = UnreachableBlocks.end(); I != E; ++I) {
BasicBlock *BB = *I;
- BB->getInstList().pop_back(); // Remove the return insn
- new BranchInst(UnwindBlock, 0, 0, BB);
+ BB->getInstList().pop_back(); // Remove the unreachable inst.
+ BranchInst::Create(UnreachableBlock, BB);
}
}
- // Now handle return blocks...
+ // Now handle return blocks.
if (ReturningBlocks.empty()) {
- ReturnBlock = 0;
+ ReturnBlock = nullptr;
return false; // No blocks return
} else if (ReturningBlocks.size() == 1) {
ReturnBlock = ReturningBlocks.front(); // Already has a single return block
}
// Otherwise, we need to insert a new basic block into the function, add a PHI
- // node (if the function returns a value), and convert all of the return
+ // nodes (if the function returns values), and convert all of the return
// instructions into unconditional branches.
//
- BasicBlock *NewRetBlock = new BasicBlock("UnifiedReturnBlock", &F);
+ BasicBlock *NewRetBlock = BasicBlock::Create(F.getContext(),
+ "UnifiedReturnBlock", &F);
- PHINode *PN = 0;
- if (F.getReturnType() != Type::VoidTy) {
+ PHINode *PN = nullptr;
+ if (F.getReturnType()->isVoidTy()) {
+ ReturnInst::Create(F.getContext(), nullptr, NewRetBlock);
+ } else {
// If the function doesn't return void... add a PHI node to the block...
- PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+ PN = PHINode::Create(F.getReturnType(), ReturningBlocks.size(),
+ "UnifiedRetVal");
NewRetBlock->getInstList().push_back(PN);
- new ReturnInst(PN, NewRetBlock);
- } else {
- // If it returns void, just add a return void instruction to the block
- new ReturnInst(0, NewRetBlock);
+ ReturnInst::Create(F.getContext(), PN, NewRetBlock);
}
// Loop over all of the blocks, replacing the return instruction with an
// unconditional branch.
//
- for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
+ for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
E = ReturningBlocks.end(); I != E; ++I) {
BasicBlock *BB = *I;
// Add an incoming element to the PHI node for every return instruction that
// is merging into this new block...
- if (PN) PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
+ if (PN)
+ PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
BB->getInstList().pop_back(); // Remove the return insn
- new BranchInst(NewRetBlock, 0, 0, BB);
+ BranchInst::Create(NewRetBlock, BB);
}
ReturnBlock = NewRetBlock;
return true;
}
-
-} // End llvm namespace
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